WO2006123494A1

WO2006123494A1 - Rotary expansion machine and refrigeration cycle device

Info

Publication number: WO2006123494A1
Application number: PCT/JP2006/308076
Authority: WO
Inventors: Hiroshi Hasegawa; Masaru Matsui; Atsuo Okaichi; Tomoichiro Tamura; Takeshi Ogata
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2005-05-16
Filing date: 2006-04-17
Publication date: 2006-11-23
Also published as: JP2008190723A

Abstract

A rotary expansion machine (100) has three-staged expansion mechanism sections (601, 602, 603) sequentially axially arranged in a manner to share a shaft (61). The expansion mechanism sections (601, 602, 603) have cylinders (62, 63, 64), pistons (67, 68, 69) installed on the shaft (61) and eccentrically rotated inside the cylinders (62, 63, 64), and partition members (70, 71, 72) each partitioning a space between a cylinder (62, 63, 64) and a piston (67, 68, 69) into a suction side space and a discharge side space. A first operation chamber for expanding refrigerant at a first expansion ratio is formed by the discharge side space of the first expansion mechanism section (601) and the suction side space of the second expansion mechanism section (602). A second operation chamber for expanding the refrigerant at a second expansion ratio greater than the first expansion ratio is formed by the discharge side space of the second expansion mechanism section (602) and the suction side space of the third expansion mechanism section (603).

Description

Rotary expander and refrigeration cycle apparatus

Technical field

TECHNICAL FIELD [0001] The present invention relates to an expander that operates by a high-pressure compressive fluid to generate power, and in particular, an expander that can recover expansion power of a refrigerant by replacing an expansion valve in a refrigeration cycle apparatus. It is about. The present invention also relates to a refrigeration cycle apparatus equipped with the expander.

Background art

A power recovery type refrigeration cycle apparatus that recovers expansion energy of a refrigerant (working fluid) with an expander and compresses the refrigerant with a compressor is used as part of work. Figure 16

1 shows a conventional refrigeration cycle apparatus using an expander. This refrigeration cycle apparatus includes a refrigerant circuit in which a compressor 1, a gas cooler 2, an expander 3, and an evaporator 4 are connected in this order. An electric motor 5 is connected to the compressor 1, and a generator 6 is connected to the expander 3. The refrigerant is compressed to high temperature and high pressure in the compressor 1 and then cooled in the gas cooler 2. Then, after expanding to low temperature and low pressure in the expander 3, it is heated in the evaporator 4. The expander 3 recovers the expansion energy of the refrigerant as mechanical energy, and then converts it into electrical energy by the generator 6. The obtained electric energy is used as a part of electric energy necessary for the electric motor 5 to drive the compressor 1.

[0003] One type of expander is a one-piston rotary type. However, because of the structure of a one-piston rotary expander, some mechanism is necessary for confining the refrigerant in the working chamber for expansion. For example, a rotary expander disclosed in JP-A-8-82296 and JP-A-8-338356 forms a refrigerant passage in the shaft, and intermittently enters the working chamber as the shaft rotates. A mechanism for sucking refrigerant is used. Further, the rotary expander disclosed in Japanese Patent Publication No. 2001-153077 employs a mechanism that controls the intake Z discharge of the refrigerant with a valve mechanism. However, in these types of expanders, the refrigerant is sucked intermittently, so vibration and noise tend to be relatively large. [0004] Further, Japanese Patent Laid-Open No. 2003-172244 discloses a rotary expander that allows a refrigerant to be trapped in a working chamber by forming a refrigerant suction hole in a plate that closes the top or bottom of a cylinder. It is disclosed. This rotary expander is advantageous in terms of structure because it does not require a mechanism for controlling the suction Z discharge of refrigerant. On the other hand, this rotary expander can only achieve an extremely small expansion ratio and is difficult to put into practical use.

[0005] In recent years, in order to improve these problems, a rotary expander in which one working chamber is formed by two upper and lower cylinders has been developed and disclosed in a pamphlet of WO2005Z026499. According to this rotary expander, continuous suction of refrigerant can be realized, so that vibration and noise can be reduced, and a practically sufficient expansion ratio can be achieved.

On the other hand, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-364562, another type of expander is a scroll type. The scroll type expander essentially eliminates the need for a mechanism for controlling the suction and discharge of refrigerant, and can achieve a practically sufficient expansion ratio.

Disclosure of the invention

Next, FIG. 17 shows a Mollier diagram of a refrigeration cycle in which carbon dioxide is used as a refrigerant and power recovery is performed by an expander. Process AB corresponds to the change in compressor 1, Process BC in gas cooler 2, Process CD in expander 3, and Process DA in evaporator 4. However, in compressor 1 and expander 3, an adiabatic change (isentropic change) is assumed. The refrigerant is a supercritical single phase at point C before it is dissipated by the gas cooler 2 and sucked into the expander 3, and at point D before it is expanded by the expander 3 and guided to the evaporator 4. Two phases. In other words, in the expander 3, the refrigerant expands as a single phase up to point E on the point C force saturated liquid line, and expands from point E to point D with a phase change to liquid force gas.

[0008] The graph in FIG. 18 represents the relationship between the pressure of the refrigerant and the specific volume in the expansion process CD.

The points C, D, and E in Fig. 18 are the same as the points C, D, and E in Fig. 17. Expansion process The refrigerant in CE is very dense and close to an incompressible fluid. Moreover, the pressure drop (Ps to Pm) in the expansion process CE reaches nearly half of the pressure drop (Ps to Pd) of the total expansion process CD. However, the specific volume of the refrigerant hardly increases because it is close to an incompressible fluid. In contrast, in the expansion process ED, the phase changes from the liquid phase to the gas phase. Due to the expansion, the specific volume of the refrigerant is greatly increased. As described above, in the expander of the power recovery type refrigeration site apparatus, the change rate of the specific volume of the refrigerant greatly changes with the saturated liquid line as a boundary. Specifically, the rate of change in specific volume is greater after entering the gas-liquid two-phase region.

On the other hand, according to the rotary expander disclosed in the pamphlet of WO2005Z026499, the volume (vertical axis V) of one working chamber formed by two upper and lower cylinders as shown in FIG. Axis T), in other words, increases sinusoidally with respect to the rotation angle of the shaft. Here, the correspondence between the characteristic diagram of FIG. 19 and the expansion process of the refrigerant described in FIGS. 17 and 18 is verified. According to the knowledge of the present inventors, the ratio between the change rate of the specific volume in the expansion process CE and the change rate of the specific volume in the expansion process ED depends on the operating conditions of the refrigeration cycle apparatus, but is a carbon dioxide refrigerant. For example, 1.1: 2.5. Based on this knowledge, the specific volume of refrigerant at point E on the saturated liquid line (see Figs. 17 and 18) is added to Fig. 19, and the correspondence between the specific volume of refrigerant and the rotation angle of the shaft is found. Then, it can be seen that the expansion process CE is completed after only a short time has passed for the expansion start (T = 0) force. As explained above, in the expansion process CE, although the specific volume does not increase much, the pressure drop reaches about half of the total expansion process CD. In other words, the refrigerant pressure drops abruptly when the force shaft at the start of expansion rotates slightly. A sudden pressure drop is thought to hinder efficient power recovery.

[0010] As a method for coping with the change in the change rate of the specific volume accompanying such a phase change, the above Japanese Unexamined Patent Publication No. 2000-364562 adjusts the thickness of the wrap of the scroll expander, and A method is disclosed in which the volumetric change rate is reduced in the first half of the expansion process and increased in the second half of the expansion process.

[0011] However, as explained in FIG. 18, the ratio of the change rate of the specific volume in the expansion process CE and the change rate of the specific volume in the expansion process ED is, for example, 1. 1: 2 .5 and big. It is unrealistic in terms of the structure of the scroll expander to produce such a difference in volume change rate between the first half and the second half of the expansion process by adjusting the wall thickness of the wrap.

[0012] The present invention has been made in view of the points to be worked on, and realizes a volume change rate of the working chamber adapted to the phase change of the expansion process, thereby providing a highly efficient expander. Objective. Also A refrigeration cycle apparatus including the expander is provided.

That is, the present invention includes a force cylinder, a shaft that passes through the cylinder, a piston that is attached to the shaft and rotates eccentrically inside the cylinder, and a space between the cylinder and the suction side space and a discharge side. First, second, and third expansion mechanism portions that are arranged in order in the axial direction so as to share a shaft and have a partition member that partitions into a space;

A suction path for sucking the working fluid into the suction side space of the first expansion mechanism,

A first communication path that connects the discharge-side space of the first expansion mechanism and the suction-side space of the second expansion mechanism to form a first working chamber that expands the working fluid at a first expansion ratio;

The discharge-side space of the second expansion mechanism and the suction-side space of the third expansion mechanism are connected to form a second working chamber that further expands the working fluid expanded in the first working chamber at the second expansion ratio. The second communication passage,

Disclosed is a rotary expander that includes a discharge-side spatial force of a third expansion mechanism section and a discharge path that discharges a working fluid, and has a second expansion ratio larger than the first expansion ratio.

[0014] The rotary expander of the present invention uses a three-stage cylinder and expands the working fluid (specifically, refrigerant) stepwise in the two working chambers of the first working chamber and the second working chamber. This is what I did. The second expansion ratio of the second working chamber is larger than the first expansion ratio of the first working chamber, that is, the volume change rate in the first half of the expansion process is small and the volume change rate in the second half of the expansion process is large. It has become. In particular, with a rotary expander, the number of cylinders is three or more, so that there is a large difference between the volume change rate in the first half of the expansion process and the volume change rate in the second half of the expansion process compared to the scroll type. It is possible to have it. Therefore, according to the present invention, it is possible to provide an expander that is excellent in power recovery efficiency and is adapted to the change in the change rate of the specific volume of the refrigerant in the expansion process.

Brief Description of Drawings

[0015] FIG. 1 is a longitudinal sectional view of an expander according to the present invention.

[Figure 2] Plan view of the expansion mechanism

FIG. 3A is a plan view and a sectional view of the first intermediate plate shown in FIG.

FIG. 3B is a plan view and a sectional view of the second intermediate plate shown in FIG.

圆 4] Enlarged sectional view of expansion mechanism unit [Fig.5] Principle of operation of the expander in Fig.1

[Fig. 6A] Graph showing the relationship between shaft rotation angle and working chamber volume

[Fig. 6B] Graph showing the relationship between shaft rotation angle and refrigerant pressure

[Fig. 7] Graph of the results of a computer simulation study of the relationship between the expansion ratio in the single-phase expansion process of carbon dioxide refrigerant and the suction temperature of the expander

[Fig. 8] Graph of the results of a computer simulation study of the relationship between the expansion ratio of the diacid carbon refrigerant during the entire expansion process and the suction temperature of the expander

FIG. 9 is a graph showing the relationship between the ratio of the change rate of the specific volume in the entire expansion process to the change rate of the specific volume in the single-phase expansion process and the suction temperature of the expander

[Fig. 10A] Mollier line explaining the effect of completing the single-phase expansion process in the first working chamber.

[Fig. 10B] Mollier line explaining the problem of dragging the single-phase expansion process to the second working chamber

[Fig.11] Explanatory diagram of phenomenon caused by sudden pressure drop

FIG. 12 is a longitudinal sectional view of the expander according to the second embodiment.

FIG. 13 is a plan view of the main part of the expander of FIG.

FIG. 14 is a plan view of a principal part showing a modification of the expander of FIG.

FIG. 15 is a plan view of relevant parts showing another modification of the expander shown in FIG.

[Fig.16] Block diagram of a conventional power recovery refrigeration system using an expander

[Fig.17] Mollier diagram of refrigeration cycle of diacid-carbon refrigeration

FIG. 18 is a graph showing the relationship between refrigerant pressure and specific volume during the expansion process.

FIG. 19 is a characteristic diagram showing the change in volume with time of a conventional expander

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of an expander according to the present invention. 2 is a plan view of the first expansion mechanism portion, the second expansion mechanism portion, and the third expansion mechanism portion of the expander of FIG. 1 observed from a direction parallel to the shaft rotation axis (hereinafter referred to as the axial direction). is there. As shown in FIG. 1, the expander 100 is a rotary expander. In this specification, among the rotary expanders, the rolling The power of the present invention can be explained as an example. The present invention can also be applied to a so-called swing-type rotary expander.

As shown in FIG. 1, the expander 100 includes a sealed container 51, a rotary type expansion mechanism unit 60 accommodated in the sealed container 51, and a generator 52 also accommodated in the sealed container 51. I have. An oil reservoir 54 is formed below the sealed container 51. Oil is also supplied to each sliding portion of the expansion mechanism unit 60 via the oil hole (not shown) in the shaft 61, and the lower end portion of the shaft 61 is lubricated and sealed. The generator 52 includes a rotor 52a and a stator 52b. The rotor 52a is connected to the shaft 61 of the expansion mechanism unit 60, and rotates as the expansion mechanism unit 60 operates. The expansion mechanism unit 60 includes three stages of expansion mechanism portions that share the shaft 61, that is, a first expansion mechanism portion 601, a second expansion mechanism portion 602, and a third expansion mechanism portion 603. A first working chamber (first expansion chamber) for expanding the refrigerant is formed by the discharge side space of the first expansion mechanism section 601 and the suction side space of the second expansion mechanism section 602, and expands in the first working chamber. A second working chamber (second expansion chamber) for further expanding the refrigerant thus formed is formed by the discharge side space of the second expansion mechanism portion 602 and the suction side space of the third expansion mechanism portion 603. Each expansion mechanism section 601, 602, 603 is designed such that the expansion ratio of the downstream second working chamber is larger than the expansion ratio of the upstream first working chamber in the refrigerant flow direction.

[0018] The expansion mechanism portions 601, 602, and 603 include cylinders 62, 63, and 64, a shaft 61 that passes through the cylinders 62, 63, and 64, and inner shafts of the cylinders 62, 63, and 64 that are attached to the shaft 61. Partition members 70, 71, 72 (vanes) that divide the space between pistons 67, 68, 69 and cylinders 62, 63, 64 and pistons 67, 68, 69 into suction side and discharge side spaces ). The shaft 61 has eccentric portions 6 la, 61 b, 61 c at three locations along the rotation axis O. Eccentric rods 61a, 61b and 61c are located in cylinders 62, 63 and 64, respectively, and pistons 67, 68 and 69 are engaged with each other!

[0019] As shown in FIG. 2, the grooves 62a, 63a, and 64a are formed in the cylinders 62, 63, and 64 so as to extend radially outward. The partition rods 70, 71, 72ί are arranged in the grooves 62a, 63a, 64a, and can advance and retreat in two directions, a direction approaching the rotation axis O of the shaft 61 and a direction separating them. The tip of the partition member 70, 71, 72 contacts the outer peripheral surface of the piston 67, 68, 69. The space force between the cylinders 62, 63, 64 and the pistons 67, 68, 69 is divided into the suction rod J space 80a, 81a, 82a and the discharge rod J space 80b, 81b, 82b! / RU Further, springs 73, 74, and 75 are self-placed behind the partition rods 70, 71, and 72, and the partition members 70, 71, and 72 are pistoned by the inertia restoring force of the springs 73, 74, and 75. It is pressed toward 67, 68, 69.

[0020] A suction side space 80a and a discharge side space 80b are formed inside the first cylinder 62.

Similarly, a suction side space 81a and a discharge side space 81b are formed inside the second cylinder 63, and a suction side space 82a and a discharge side space 82b are formed inside the third cylinder 64. As shown in the upper diagram of FIG. 2, the first cylinder 62 is formed with a suction passage 62b for sucking the refrigerant before expansion into the suction side space 80a. A suction pipe 78 is connected to the suction path 62b for allowing the first cylinder 62 to suck the refrigerant to be expanded. On the other hand, as shown in the lower diagram of FIG. 2, the third cylinder 64 is formed with a discharge path 64b for discharging the expanded refrigerant from the discharge side space 82b. A discharge pipe 79 for sending the expanded refrigerant to the outside of the sealed container 51 is connected to the discharge path 64b.

In addition, as shown in FIG. 1, a first intermediate plate that closes the lower end of the first cylinder 62 and the upper end of the second cylinder 63 is interposed between the first expansion mechanism portion 601 and the second expansion mechanism portion 602. 65 (first intermediate member) is arranged. A second intermediate plate 66 (second intermediate member) that closes the lower end of the second cylinder 63 and the upper end of the third cylinder 64 is disposed between the second expansion mechanism 602 and the third expansion mechanism 603. It is. Further, the upper bearing member 76 that also serves as the upper end plate of the first cylinder 62 and the lower bearing member 77 that also serves as the lower end plate of the third cylinder 64 sandwich the expansion mechanism unit 60 from above and below in the axial direction. It is arranged as follows.

FIG. 3A shows a plan view and a sectional view of the first intermediate plate, and FIG. 3B shows a plan view and a sectional view of the second intermediate plate. As shown in FIG. 3A, the first intermediate plate 65 connects the discharge side space 8 Ob of the first expansion mechanism portion 601 and the suction side space 81a of the second expansion mechanism portion 602 to expand the first working chamber. A first communication hole 65a is formed as a communication passage forming 83 (see FIG. 2). As shown in FIG. 3B, the second intermediate plate 66 is connected to the discharge side space 81b of the second expansion mechanism section 602 and the suction side space 82a of the third expansion mechanism section 603, and is expanded in the first working chamber 83. A second communication hole 66a is formed as a communication path for forming a second working chamber 84 (see FIG. 2) for further expanding the refrigerant. Yes. If one working chamber is formed by such a communication hole, a special mechanism such as a valve mechanism is unnecessary, vibration and noise can be reduced, and a practically sufficient expansion ratio can be realized. Is possible.

[0023] The opening shape of the communication holes 65a, 66a is not limited to a circle, and may be an ellipse or a square.

Further, the communication holes 65 a and 66 a are oblique holes in which the center line of the force hole penetrating the intermediate plates 65 and 66 in the thickness direction is inclined with respect to the rotation axis O of the shaft 61. By forming the communication holes 65a and 66a obliquely, the positions of the partition members 70, 71 and 72 around the rotation axis O of the shaft 61 can be matched in the axial direction. Such an arrangement is advantageous for space saving of the expansion mechanism unit 60.

[0024] In the present embodiment, the diameter D2 of the second communication hole 66a is larger than the diameter D1 of the first communication hole 65a. If the aperture shape is other than circular, the size may be compared by converting it to the diameter (equivalent diameter) of a circle with the same area. The advantages of this configuration will be described later.

Next, FIG. 4 is an enlarged cross-sectional view of the expansion mechanism unit. As shown in FIG. 4, the height H2 of the second cylinder 63 in the axial direction is larger than the height HI of the first cylinder 62. Further, the height H3 of the third cylinder 64 in the axial direction is larger than the height H2 of the second cylinder 63. The cylinders 62, 63, 64 are concentric and have the same inner diameter. Also, the outer diameters of the pistons 67, 68, 69 rotating eccentrically in the cylinders 62, 63, 64 are equal. Therefore, the expansion ratio (volume change rate) of the first working chamber 83 and the expansion ratio (volume change rate) of the second working chamber 84 are based on the difference in height between the cylinders 62, 63, 64. No. In the expander 100 of the present embodiment, the heights of the cylinders 62, 63, and 64 are adjusted so that the expansion ratio of the second working chamber 84 is larger than the expansion ratio of the first working chamber 83.

Note that the expansion ratio of the first working chamber 83 is formed between the volume of the space formed between the first cylinder 62 and the first piston 67, and between the second cylinder 63 and the second piston 68. It corresponds to the ratio with the volume of the space. Similarly, the expansion ratio of the second working chamber 84 depends on the volume of the space formed between the second cylinder 63 and the second piston 68 and the space formed between the third cylinder 64 and the third piston 69. It corresponds to the ratio with the volume.

FIG. 5 is an operation principle diagram of the expander shown in FIG. 1, and shows a state where the rotation angle of the shaft 61 is 90 °. Figure 6A is a graph showing the relationship between the rotation angle of the shaft and the volume of the working chamber. FIG. 6B is a graph showing the relationship between the rotation angle of the shaft and the pressure of the refrigerant.

[0028] The refrigerant sucked into the expander 100 flows into the river pages of the first cylinder 62, the second cylinder 63, and the third cylinder 64. Piston 67, 68, 69 force S Top dead center (when the contact between the partition rod 70, 71, 72 and the piston 67, 68, 69 is the farthest away from the rotation axis O force) The rotation angle is assumed to be 0 °. As shown in FIG. 5, when the shaft 61 starts to rotate counterclockwise, the suction side space 80a of the first cylinder 62 gradually increases, and the high pressure refrigerant flows from the suction pipe 78 through the suction path 62b. 62 is sucked into the suction side space 80a. When the shaft 61 rotates 360 °, the refrigerant sucked into the suction side space 80a of the first cylinder 62 becomes the first working chamber by the discharge side space 80b of the first cylinder 62 and the suction side space 81a of the second cylinder 63. Move to 83.

When the shaft 61 further rotates, as shown in FIG. 6A, the volume of the first working chamber 83 gradually increases from Vsl to Vs2. This is because the height H2 of the second cylinder 63 is adjusted to be larger than the height HI of the first cylinder 62. In the first working chamber 83 where the difference between Vsl and Vs2 is small, the refrigerant slightly increases its specific volume. However, as shown in Fig. 6B, the refrigerant pressure decreases relatively greatly from Ps to Pm. When the shaft 61 rotates to 720 °, the refrigerant expanded in the first working chamber 83 moves to the second working chamber 84 formed by the discharge side space 81b of the second cylinder 63 and the suction side space 82a of the third cylinder 64.

When the shaft 61 further rotates, as shown in FIG. 6A, the volume of the second working chamber 84 gradually increases from Vs2 to Vs3. This is because the height H3 of the third cylinder 64 is adjusted to be larger than the height H2 of the second cylinder 63. In the second working chamber 84 where the difference between Vs2 and Vs3 is large, the refrigerant greatly increases its specific volume. At this time, as shown in FIG. 6B, the pressure of the refrigerant also changes (decreases) in Pm force to Pd. This pressure change (Pm−Pd) in the second working chamber 84 is not much different from the pressure change (Ps−Pm) in the first working chamber.

[0031] As described above, after the refrigerant expands in the first working chamber 83, it further expands in the second working chamber 84, and rotates the shaft 61 to become a low pressure. The low-pressure refrigerant is discharged from the discharge pipe 79 from the discharge side space 82b of the third cylinder 64 through the discharge path 64b.

[0032] As described above, the rate of change in the specific volume of the gas-liquid two-phase flow refrigerant such as carbon dioxide carbon dioxide or alternative chlorofluorocarbon is the single-phase expansion process (corresponding to the expansion process CE shown in FIG. 17). Gas-liquid two-phase expansion process (It corresponds to the expansion process ED shown in Fig. 17). In the present embodiment, the expansion ratio of the first working chamber 83 and the expansion ratio of the second working chamber 84 are adjusted, that is, the heights HI, H2, and H3 of the cylinders 6, 2, 63, and 64 are adjusted. As a result, the rotary expander 100 adapted to the change in the change rate of the specific volume of the refrigerant is realized.

[0033] The heights HI, H2, H3 of the cylinders 62, 63, 64 can be determined based on the facts described below.

[0034] Fig. 7 is a computer simulation showing the relationship between the expansion ratio in the single-phase expansion process (corresponding to the expansion process CE in Fig. 17) and the intake temperature of the expander according to the suction pressure. This is a graph of the results of investigation. The expansion ratio was calculated from the ratio of the specific volume of refrigerant at point C and point E (see Fig. 17) of the refrigeration cycle, assuming adiabatic change (isentropic change). The expansion ratio in the single-phase expansion process depends greatly on the intake temperature, and increases as the intake temperature increases. It also depends on the suction pressure. When the suction temperature is 35 ° C or lower, the pressure increases as the pressure increases.

[0035] Applications of the power recovery refrigeration cycle apparatus using carbon dioxide and carbon dioxide as a refrigerant include, for example, an air conditioner and a water heater. Under standard operating conditions such as air conditioning cooling or heating rating conditions, or hot water supply summer rating conditions, winter rating conditions, or mid-term rating conditions, the expander intake temperature is approximately 15 ° C to 40 ° C. C or less, suction pressure is generally 9MPa or more and 12MPa or less. Under these conditions, it can be seen from FIG. 7 that the expansion ratio in the single-phase expansion process is 1.1 or less, except when the suction pressure is 9 MPa and the suction temperature is 40 ° C. Even if the suction pressure is 9 MPa, the expansion ratio is below 1.1 at a suction temperature of about 38 ° C. In addition, under the condition where the suction temperature is 35 ° C, the expansion ratio in the single-phase expansion process is 1.07 or less at any suction pressure.

[0036] Next, FIG. 8 shows, for each suction pressure, the expansion ratio in the entire expansion process of the carbon dioxide refrigerant (corresponding to the expansion process CD in FIG. 17) and the suction temperature of the expander. It is the graph of the result of having investigated the relationship in the computer simulation. The discharge pressure was set at 4. OMPa, and the expansion ratio for the entire expansion process was determined by the specific force of the specific volume of refrigerant at points C and D (see Fig. 17) of the refrigeration cycle. It can be seen that the expansion ratio throughout the expansion process is distributed around 2.0, although it varies depending on the conditions. [0037] FIG. 9 shows a ratio X (vertical axis) of the specific volume change rate in the entire expansion process to the specific volume change rate in the single-phase expansion process based on the simulation results of FIGS. 7 and 8. And a graph showing the relationship between the suction temperature (horizontal axis) of the expander and the suction pressure. The ratio X was calculated using the following formula 1. In Equation 1, R1 is the expansion ratio in the single phase, and R is the expansion ratio in the entire expansion process.

[0038] (Formula 1)

[0039] As shown in FIG. 9, under any condition, the change rate of the specific volume in the entire expansion process of the refrigerant is 22 times as much as the 5 times the change rate of the specific volume in the single phase expansion process. is there. The expansion ratio in the single phase expansion process is very small compared to the rate of change in specific volume throughout the expansion process!

[0040] According to the above knowledge, for example, the expansion ratio of the first working chamber 83 can be set to about 1.1, and the expansion ratio of the second working chamber 84 can be set to about 1.8.

[0041] Under the condition that the inner diameters of the first cylinder 62, the second cylinder 63 and the third cylinder 64 are equal and the diameters of the first piston 67, the second piston 68 and the third piston 69 are equal, The expansion ratio of the first working chamber 83 matches the ratio of the height HI of the first cylinder 62 and the height H2 of the second cylinder 63, and the expansion ratio of the second working chamber 84 matches the height H2 of the second cylinder 63. It corresponds to the ratio of 3 cylinder 64 height H 3.

[0042] One important problem in setting the expansion ratio of the first working chamber 83 and the second working chamber 84 as described above is that the single-phase expansion process is completed in the first working chamber 83. The question is whether the single-phase expansion process should be continued in the second working chamber 84. If the former is added to the Mollier diagram, it can be represented as shown in Fig. 10A. That is, the expansion process in the first working chamber 83 is CQ, and the expansion process in the second working chamber 84 is QD. On the other hand, the latter is added to the Mollier diagram

1 1

Then, it can be expressed as shown in Fig. 10B. That is, the expansion process in the first working chamber 83 is C Q, and the expansion process in the second working chamber 84 is Q D. The difference between the two is the expansion in the first working chamber 83.

twenty two

Point Q and point Q representing the boundary between tension and expansion in the second working chamber 84 1S Lower pressure than saturated liquid line

1 2

The side or the high pressure side. Among these, more preferable is an example in which the single-phase expansion process CE is completed in the first working chamber 83 as shown in FIG. 10A.

[0043] First, according to the example of FIG. 10B, the single-phase expansion process CE is changed to the second working chamber 84 having a large expansion ratio. Will be dragged. Then, the expansion process QE, which is part of the single-phase expansion process CE, expands

2

This is performed in the second working chamber 84 having a large ratio, and a sudden pressure drop of the refrigerant occurs although it is instantaneous. Although it is not always clear, a sudden pressure drop is accompanied by a phase change delay as shown in Fig. 11, and may cause a recovery loss of expansion energy. Therefore, the method of expansion that involves a sudden pressure drop should also be avoided as it has the power of efficient power recovery.

On the other hand, according to the example of FIG. 10A, the single-phase expansion process CE is completed in the first working chamber 83.

That is, in the first working chamber 83, since the refrigerant expands from a single phase to a gas-liquid two phase, there is no problem of a rapid pressure drop. Therefore, the pressure drop in the single phase can be alleviated while maintaining the expansion ratio necessary for the entire expansion process, and the expansion energy of the refrigerant can be recovered efficiently.

[0045] Further, by making the diameter D1 of the first communication hole 65a smaller than the diameter D2 of the second communication hole 66a, the volume of the first communication hole 65a is died in the specific volume force, in the single phase expansion process. This prevents the refrigerant from re-expanding and lowering the efficiency of the expander, and the specific volume is large.In the gas-liquid two-phase expansion process, the pressure loss when the refrigerant passes through the second communication hole 66a is reduced. It can be stopped to a minimum. Therefore, the power recovery efficiency of the expander 100 can be improved.

In the present embodiment, the vertical upward force is also applied to the first cylinder 62, the second cylinder 63, and the third cylinder 64 along the axial direction so that the refrigerant flows with a vertical upward force directed downward. Arranged in order. According to such a configuration, the liquid refrigerant having a high density drops in the first communication hole 65a formed in the first intermediate plate 65 and the second communication hole 66a formed in the second intermediate plate 66 by gravity. If high-density liquid refrigerant stays in each of the communication holes 65a and 66a, which become a dead space in the expander, the expansion efficiency of the expander is reduced. According to this embodiment, such a phenomenon can be prevented and an expander with high expansion efficiency can be realized.

[0047] (Second embodiment)

The expansion ratio of the first working chamber and the expansion ratio of the second working chamber can be set to the desired values by combining parameters such as the inner diameter and height of the cylinder or the diameter of the piston in various patterns. Is possible. The rotary expander 20 of the present embodiment shown in FIG. 0 creates a suitable expansion ratio of the first working chamber and that of the second working chamber by adjusting the inner diameters of the cylinders 21, 22, 23 and the diameters of the pistons 41, 42, 43, etc. . Since the other basic configuration is the same as that of the expander of the first embodiment, the description thereof is omitted.

In the rotary expander 200 of the present embodiment, the inner diameter D1 of the first cylinder 21 is equal to the inner diameter D2 of the second cylinder 22 as shown in the plan view of the main part of FIG. D3 is larger than the inner diameter D2 of the second cylinder 22. Also, the eccentric amount E3 of the third eccentric portion 31c where the eccentric amount E1 of the first eccentric portion 31a is equal to the eccentric amount E2 of the second eccentric portion 3 lb is greater than the eccentric amount E2 of the second eccentric portion 3 lb. It ’s big. Further, the outer diameter Dp2 of the second piston 42 is smaller than the outer diameter Dpi of the first piston 41, and the outer diameter Dp3 of the third piston 43 is larger than the outer diameter Dp2 of the second piston 42. These dimensions are adjusted so that the expansion ratio of the first working chamber and the expansion ratio of the second working chamber are within the ranges described in the first embodiment.

[0049] Under the condition that the heights of the first cylinder 21, the second cylinder 22 and the third cylinder 23 are equal, the dimensions of each part may be adjusted as shown in the plan view of the main part in FIG. it can. In the example of FIG. 14, the outer diameters of the first piston 41, the second piston 42, and the third piston 43 are equal to each other. In this case, the expansion ratio of the first working chamber and the expansion ratio of the second working chamber can be adjusted by making the inner diameters of the cylinders 21, 22, and 23 different. That is, the inner diameter of each cylinder 21, 22, 23 is set as D1 <D2 <D3! The shaft 31 force is also used for each piston 41, 42, 43, and the outer diameter force S of each piston 41, 42, 43 is equal, and the inner diameter of each cylinder 21, 22, 23 is different. The eccentricity of 31b and 31c is E1 <E2 <E3. The amount of eccentricity of the eccentric portion corresponds to the distance between the rotation axis O of the shaft 31 and the centers of the pistons 41, 42, and 43.

[0050] Under the condition that the heights of the first cylinder 21, the second cylinder 22 and the third cylinder 23 are equal, the dimensions of each part may be adjusted as shown in the plan view of the main part in FIG. it can. In the example of FIG. 15, the inner diameters of the first cylinder 21, the second cylinder 22, and the third cylinder 23 are equal. In this case, the expansion ratio of the first working chamber and the expansion ratio of the second working chamber can be adjusted by making the outer diameters of the pistons 41, 42, 43 different. That is, the outer diameter of each piston 41, 42, 43 is set to 0 1> 0 2> 0 3. Also, the eccentricity El, E2, E3 of each eccentric part 31a, 31b, 31c provides the optimum clearance between piston 41, 42, 43 and cylinder 21, 22, 23. Adjust to ensure.

[0051] According to these embodiments, since each cylinder or each piston can also produce a material (steel plate) force having the same thickness, an improvement in productivity and a reduction in cost can be expected. Also, a small and compact expander can be realized by sufficiently reducing the axial height.

As described above, in the first embodiment and the second embodiment, the case where there are three cylinders has been described, but the number of cylinders is not limited to three. That is, the number of cylinders can be increased so that three or more working chambers having different expansion ratios are formed. If the number of working chambers is increased in this way, an optimal expansion process can be realized depending on the refrigerant state when the refrigerant expands, the expansion process from the supercritical state to the saturated liquid line, or near the saturated liquid line. It is possible to control the expansion process more precisely.

In the first embodiment and the second embodiment, the refrigerant is described as carbon dioxide, but the present invention is applied to the case where the refrigerant is flon or the like and is expanded from a liquid single phase to a gas-liquid two phase through a saturated liquid. However, the same effect can be obtained.

As described above, the rotary expander of the present invention is useful as power recovery means by recovering the expansion energy of the working fluid in the refrigeration cycle. Specifically, as described in FIG. 16, the compressor that compresses the refrigerant as the working fluid, the radiator that cools the refrigerant compressed by the compressor, and the refrigerant that is cooled by the radiator are expanded. The rotary expander 100 of the present invention can be suitably used for a refrigeration cycle apparatus that includes an expander and an evaporator that evaporates the refrigerant expanded in the expander. The present invention is particularly useful when using carbon dioxide as a refrigerant.

Claims

The scope of the claims

[1] Each includes a cylinder, a shaft that passes through the cylinder, a piston that is attached to the shaft and rotates eccentrically inside the cylinder, and a space between the cylinder and the piston through a suction side space and a discharge side. A first partition member, a first partition member, a first partition member, a second partition member, and a third expansion mechanism unit arranged in order in the axial direction so as to share the shaft. The suction path for sucking the working fluid into the suction side space, the discharge side space of the first expansion mechanism portion, and the suction side space of the second expansion mechanism portion are connected, and the working fluid is set to a first expansion ratio. A first communication passage forming a first working chamber to be expanded

The discharge side space of the second expansion mechanism portion is connected to the suction side space of the third expansion mechanism portion, and the working fluid expanded in the first working chamber is further expanded at a second expansion ratio. 2 a second communication path forming a working chamber;

A discharge path for discharging the working fluid from the discharge side space of the third expansion mechanism section,

A rotary expander in which the second expansion ratio is larger than the first expansion ratio.

[2] a first intermediate plate disposed between the first expansion mechanism portion and the second expansion mechanism portion;

A second intermediate plate disposed between the second expansion mechanism and the third expansion mechanism;

The first communication path is a first communication hole formed in the first intermediate plate;

The rotary expander according to claim 1, wherein the second communication passage is a second communication hole formed in the second intermediate plate.

[3] The inner diameter of the first cylinder, which is the cylinder of the first expansion mechanism, the inner diameter of the second cylinder, which is the cylinder of the second expansion mechanism, and the third expansion mechanism. The inner diameter of the third cylinder, which is the cylinder, is equal

The outer diameter of the first piston, which is the piston of the first expansion mechanism, the outer diameter of the second piston, which is the piston of the second expansion mechanism, and the third expansion mechanism The outer diameter of the third piston, the piston, is equal

In the axial direction, the height of the first cylinder is Hl, and the height of the second cylinder is H2. The rotary expander according to claim 1, wherein when the height of the third cylinder is H3, H1 <H2 and H3 is satisfied.

4. The rotary expander according to claim 3, wherein the working fluid is configured to expand from a single phase to a gas-liquid two phase in the first working chamber.

5. The rotary expander according to claim 2, wherein an equivalent diameter of the second communication hole is larger than an equivalent diameter of the first communication hole.

[6] a compressor that compresses a refrigerant as a working fluid;

A radiator for cooling the refrigerant compressed by the compressor;

An expander for expanding the refrigerant cooled by the radiator;

An evaporator for evaporating the refrigerant expanded by the expander,

A refrigeration cycle apparatus, wherein the expander is the rotary expander according to claim 1.